1. Field of the Invention
The invention relates generally to bathtub overflow assemblies and more particularly to an overflow assembly equipped with a test cap to permit pressure testing of the waste plumbing during construction.
2. Description of the Related Art
In new construction, plumbers are required to test the assembled waste or drain plumbing of a structure before closure of wall and ceiling surfaces. Such testing is performed under pressure to detect leaks or flaws in the waste plumbing system so that such leaks are repaired while the plumbing is still easily accessible.
Bathtub overflow assemblies are well-known plumbing fixtures that connect the overflow opening of a bathtub to the bathtub drain. The overflow opening in the bathtub is typically positioned on an end wall of the bathtub at a pre-selected elevation to limit the maximum level of water in the tub and prevent bathtub overflow. Water above the level of the overflow opening is safely drained through the opening and overflow assembly into the bathtub drain.
The overflow assembly typically includes an overflow elbow having an inverted L-shape. An inlet of the overflow elbow is sealingly engaged with the bathtub overflow opening. The overflow elbow provides a flow passage extending downwardly to connect the bathtub overflow opening with the bathtub drain. There are a number of well-known arrangements for fixing the inlet of the overflow elbow to the bathtub overflow opening in sealed relationship. The integrity of this seal is important to prevent water leaking around the overflow elbow.
An overflow assembly relevant to the present invention is shown in U.S. Pat. Nos. 6,675,406 and 6,637,050. The overflow elbow is provided with a radially extending flange positioned to compress a sealing gasket against the outside surface of the tub around the tub overflow opening. A cylindrical fitting having a threaded outside surface extends through the tub overflow opening and is threadably engaged by a retainer nut that bears against the inside surface of the tub. A thin diaphragm is sealed over the end of the overflow elbow to seal the overflow inlet during testing of the drain plumbing. After testing, the thin diaphragm is cut away and a trim cap is placed over the inner end of the overflow elbow and retainer nut to provide a finished appearance to the installed assembly. One potential drawback to this approach is that the thin diaphragm can be damaged during manufacture, shipping or installation of the overflow assembly. A damaged diaphragm would require replacement of the overflow elbow or some alternative means of sealing the overflow inlet during testing of the drain plumbing.
It is also known to provide a threaded test cap separate from the threaded retainer nut to cover the overflow inlet during testing of the drain plumbing. After testing, the test cap is unthreaded from the inner end of the overflow elbow and the decorative cap is installed. Manufacture and packaging of separate retainer nuts and test caps is costly and presents the potential that one or the other may be omitted from the packaged assembly.
A further alternative overflow assembly configuration is disclosed in U.S. Pat. No. 6,484,331 (the '331 patent). The '331 patent overflow assembly includes an overflow elbow having an internally threaded overflow opening that receives one end of an externally threaded overflow cap extending through the tub overflow opening. A gasket is compressed between the overflow elbow and the outside surface of the tub around the overflow opening. The overflow cap includes a test cap molded integrally with the overflow cap. The test cap is molded with a thin, breakable connection to the overflow cap such that, after testing of the drain plumbing system, the test cap is broken away from the overflow cap to open the overflow inlet. A potential drawback of the '331 overflow assembly structure is that the threaded joint between the overflow cap and the overflow elbow is positioned outside the tub. This presents the potential for leakage that is not present in an overflow elbow configured to extend integrally through the tub overflow opening.